Oh so you have another fan, but it just isn't plugged in. Yeah you can probably find an adaptor somewhere; I know some fans come with them, doesn't sound like yours did though (wait..no, why doesn't it work again? sorry). If it's in the front, it is almost certainly an intake fan. If you're only going to have one fan in your case (working, that is) it should be an exhaust like you are doing now.